The role of the Río de la Plata bottom salinity front in accumulating debris

The Río de la Plata, one of the most important South American estuarine environments, is characterized by a bottom salinity front that generates an ecotone between the river and the estuary. Based on bottom trawls and costal sampling we describe the distribution, types, and amount of debris found in the bottom and shoreline across this front. Plastics and plastic bags were the main debris types in both areas. Concentrations of total debris upriver the front were always significantly higher than downriver the front showing that the front acts as a barrier accumulating debris. Moreover, a large part of debris end ups accumulated in the coastal area upriver the frontal position. This area is particularly sensitive because the coastline encompasses an UNESCO Man and the Biosphere Reserve and a Ramsar site, and due to the ecological significance of the front for many valuable species.     

Analytical procedure for simultaneous use of seven fluorobenzoates in multitracer tests

An analytical procedure allowing simultaneous use of seven fluorobenzoate (FBA) isomers was developed and examined through column and field tracer experiments. The analytical method, based on high performance liquid chromatography (HPLC), included a reverse-phase separation method. This method was found to be very efficient for the FBA analysis, allowing accurate determination of seven FBAs in a single HPLC run, while avoiding analytical interference of other natural water constituents or pollutants. Consequently, this separation method allows the simultaneous use of seven isomers in multitracer tests in highly saline or contaminated environments. The mobility properties of the FBAs were examined in percolation experiments through a column filled with a mixture of crushed chalk and common fracture filling and coating material. The FBAs behaved conservatively as compared to bromid. All seven FBA isomers were successfully used in a multitracer test in a field percolation experiment designed to identify flowpath along a fracture plane.     

岩溶灾害对民用建筑和工业建筑影响的评价

欧洲部分覆盖着发育良好的硫酸盐和碳酸盐岩溶,主要赋存于沉积覆盖较薄的河谷之中。这种条件有利于岩溶崩塌的发育。岩溶崩塌是民用建筑和工业建筑的主要威胁。岩溶岩石的演化包含了若干个岩溶发育时代,它们造成岩溶岩石中溶洞的生成,其结果形成地表     

Hydrogeological Characteristics of a Karst Mountainous Catchment in the Northwest of Vietnam

This paper presents a preliminary assessment of the hydrogeological characteristics of a karst mountainous catchment, the Suoi Muoi River catchment, in the northwest of Vietnam. The catchment is located at 600 -700 m a.s.l. and covers an area of 284 km. Exposed limestone occupies 32% of the total catchment area. Various types of assessments have been carried out, including geological and hydrogeological field surveys, cave surveys, dye-tracer tests, meteorological and surface water monitoring. Geological studies and cave surveys have identified the most important active cave/conduit systems within the catchment. Although these data are essential, they are insufficient to make a comprehensive appraisal of the hydrologic nature of the catchment under interest. An attempt was made to calculate a global water balance of the catchment, based on short-term (15 months) meteorological and streamflow records. The results show that, despite the existence of a number of substantial cavem conduit systems, the groun     

高岭土有机改性实验研究

利用二甲亚砜、丙烯酰胺、硅烷等多种有机改性剂对高岭土进行了有机夹层、吸附改性。经有机改性。高岭石的层面间距d（001）可增大到1.1454nm，并且与丙烯酰胺加热后形成稳定的了聚丙烯酰胺-高岭土有机无机复合材料，与硅烷形成稳定的有机无机复合体。改性后的高岭土与有机物的相溶性大大提高，从而为更好地开发应用高岭土做准备。     

小口径油井钻进

本文所涉及的是孔径为152mm(表层导向管除外），或小于此种直径的海上油井，其终孔最大直径为100mm或更小。井深不超过2500m，这种情况将近占全部油井的80％，小口径钻进还包括微钻进和超小径钻进。由于孔径缩小，因此套管与钻杆的环隙面积均很小，常使泥浆和钻屑的体积减少90％以上。     

具有加长工作机构的Д2-195螺杆孔底马达的应用效果

螺杆孔底马达在低速回转钻进中被广泛采用,但在使用高磨蚀性的钻井液时,它的有效使用受到马达工作机构寿命的限制.目前,提高马达组合件寿命的主要设计方法之一是增加马达工作机构的长度(即转子一定子工作副的有效长度l).这种加长的工作机构能通过降低定子—     

冲击作用的Г3A型孔底液压冲击机械

冲击机械(见图)应用于在Ⅶ级和Ⅶ级以上可钻性的岩石中钻进勘探钻孔。机械工作时,是沿着用活阀作液体分配系统的直线运动。液压冲击器的作用原则,是基于利用自地表经过钻杆压入的冲洗液能量。在机械中冲击锤脉冲转变而得到的动能对铁砧造成冲击,此铁砧是与岩心管及岩石破碎工具紧紧的联结着。与此同时,液压冲击器及岩石破碎工具则用一般的方法通过空心钻杆令其回转。